Quantum-enhanced interferometry for new physics

现代物理学解释了从最小尺度到最大尺度的各种惊人的现象，并且已经彻底改变了世界！激光、半导体和晶体管是我们的笔记本电脑、手机和医疗设备的核心。每年，英国和世界各地的国家量子技术计划都在开发新的量子技术，这些技术影响着我们的日常生活和导致新发现的基础物理研究。光的量子态最近提高了引力波探测器的灵敏度，迄今为止，引力波探测器的探测已经吸引了公众，超导过渡边缘传感器现在被用于天文实验，可以制作出高分辨率的宇宙图像。尽管现代物理学取得了成功，但仍然存在一些深刻而具有挑战性的问题。我们的联盟将利用量子技术的最新进展来解决两个最紧迫的问题：(1)暗物质的本质是什么；(2)如何将量子力学与爱因斯坦的相对论结合起来？第一个研究方向是由大量的观测所推动的，这些观测表明，星系中有很大一部分物质是光学望远镜无法直接观测到的。这种神秘的物质有引力作用，但似乎不发出任何光。了解暗物质的本质将揭示宇宙的历史和星系的形成，并将引发基础物理学和应用物理学的新研究领域。尽管它非常重要，但暗物质的本质仍然是一个谜。世界范围内许多最先进的实验都在寻找暗物质的候选者，但到目前为止还没有运气。我们建议寻找的候选者是轴子和类轴子粒子（ALPs）。这些粒子是由粒子物理学中悬而未决的问题激发的，如果不是暗物质的全部，也可能是暗物质的重要组成部分。首先，我们提出了一个实验，该实验将依赖于光的量子态，并将探测暗物质信号或将现有的轴子-光子耦合限制提高几个数量级，用于大范围的轴子质量。第二，构建量子传感器，将国际100m长的ALPS探测器对类轴子粒子的灵敏度提高3 - 10倍。我们的第二个研究方向是空间和时间的本质。b谷歌最近宣布的Sycamore量子计算机和引力波探测为量子力学和爱因斯坦相对论的成功实验测试提供了额外的证据。但是如何将引力与量子力学结合起来呢？为了寻找这个问题的答案，我们建议研究时空的两个量子方面。首先，我们将实验研究全息原理，该原理表明体积的信息内容可以在其边界上编码。我们将利用光的量子态，建造两个超灵敏的激光干涉仪，以前所未有的灵敏度研究空间不同区域之间可能的相关性。其次，我们将寻找近似解决量子引力问题的半经典引力模型的特征。我们将建立两个光学干涉仪，并首次在低温硅镜的运动中寻找半经典重力的特征。在现代量子技术的帮助下，回答这些具有挑战性的基础物理学问题，有可能为物理学研究开辟新的视野，并达到对我们生活的世界的理解的新水平。提出的研究方向共享量子增强干涉测量的共同技术平台，并受益于参与该计划的研究人员的不同技能。

Modern physics explains a stunning variety of phenomena from the smallest of scales to the largest and has already revolutionized the world! Lasers, semi-conductors, and transistors are at the core of our laptops, cellphones, and medical equipment. And every year, new novel quantum technologies are being developed within the National Quantum Technology Programme in the UK and throughout the world that impact our everyday life and the fundamental physics research that leads to new discoveries. Quantum states of light have recently improved the sensitivity of gravitational-wave detectors, whose detections to date have enthralled the public, and superconducting transition-edge-sensors are now used in astronomy experiments that make high-resolution images of the universe. Despite the successes of modern physics, several profound and challenging problems remain. Our consortium will use recent advances in quantum technologies to address two of the most pressing questions: (i) what is the nature of dark matter and (ii) how can quantum mechanics be united with Einstein's theory of relativity?The first research direction is motivated by numerous observations which suggest that a significant fraction of the matter in galaxies is not directly observed by optical telescopes. This mysterious matter interacts gravitationally but does not seem to emit any light. Understanding the nature of dark matter will shed light on the history of the universe and the formation of galaxies and will trigger new areas of research in fundamental and possibly applied physics. Despite its remarkable importance, the nature of dark matter is still a mystery. A number of state-of-the-art experiments world-wide are looking for dark matter candidates with no luck to date. The candidate we propose to search for are axions and axion-like-particles (ALPs). These particles are motivated by outstanding questions in particle physics and may account for a significant part, if not all, of dark matter. First, we propose an experiment which will rely on quantum states of light and will detect a dark matter signal or improve the existing limits on the axion-photon coupling by a few orders of magnitude for a large range of axion masses. Second, we will build a quantum sensor which will improve the sensitivity of the international 100-m long ALPS detector of axion-like-particles by a factor of 3 - 10.Our second line of research is devoted to the nature of space and time. Recent announcements of Google's Sycamore quantum computer and the detection of gravitational waves have provided additional evidence to the long list of successful experimental tests of quantum mechanics and Einstein's theory of relativity. But how can gravity be united with quantum mechanics? To seek answers that inform this question, we propose to study two quantum aspects of space-time. First, we will experimentally investigate the holographic principle, which states that the information content of a volume can be encoded on its boundary. We will exploit quantum states of light and build two ultra-sensitive laser interferometers that will investigate possible correlations between different regions of space with unprecedented sensitivity. Second, we will search for signatures of semiclassical gravity models that approximately solve the quantum gravity problems. We will build two optical interferometers and search for the first time for signatures of semiclassical gravity in the motion of the cryogenic silicon mirrors.Answering these challenging questions of fundamental physics with the aid of modern quantum technologies has the potential to open new horizons for physics research and to reach a new level of understanding of the world we live in. The proposed research directions share the common technological platform of quantum-enhanced interferometry and benefit from the diverse skills of the researchers involved in the programme.